Patients are paying more for type-2 diabetes medications, and a team of Yale University researchers attributes the jump to patient migration from synthetic human and animal insulin to analog insulins.

The study showed the median amount privately insured patients shelled out for diabetes medications rose from $19 to $36 per prescription between 2000 and 2010. Researchers noted analog insulins offer flexible dosing and promise reduced nighttime hypoglycemia, but the difference in severe hypoglycemic events “was not statistically significant.”

The cost information may not be a surprise—Express Scripts reported in April that diabetes was among the top-10 most expensive traditional medication categories. The PBM said at the time that use of diabetes medications jumped 14% between 2012 and 2013, and that the amount patients spent on prescription diabetes control beat out the amount of money spent on cholesterol and blood pressure medications.

While both reports show an uptick in patients and use, the latest Centers for Disease Control and Prevention data indicates the actual diabetic population may be much greater and the long-term costs associated with the disease more burdensome. The CDC’s latest diabetes patient count is 29.1 million patients, or just over 9% of the US, has diabetes. The asterisk: 8.1 million of these patients do not know they have diabetes.

In addition to the undiagnosed, the CDC also notes that around 37% of US adults qualify as pre-diabetic. This means around 86 million adults could tip into the diabetes category, diagnosed or otherwise.

Controlling the condition itself is imperative because the disease is associated with a slew of conditions, including blindness, kidney disease, heart disease and stroke.